EA030998B1 - Ventilation system and associated operating method for use during a serious incident in a nuclear plant - Google Patents

Abstract

A ventilation system (2) for an operating room accessible to service personnel in a nuclear plant, in particular a control room (4) in a nuclear power plant (6), is intended to enable a supply of decontaminated fresh air at least for a time span of a few hours in the event of serious incidents involving the release of radioactive activity. In particular, the content of radioactive inert gases in the fresh air supplied to the operating room should be as low as possible. According to the invention, the ventilation system (2) is equipped with an air supply line (10) guided from an external inlet (14) to the operating room, with a first fan (12) and a first inert gas adsorber column (e.g. 38) being connected to said air supply line (10), an air discharge line (44) guided from the operating room to an external outlet (72), with a second fan (46) and a second inert gas adsorber column (e.g. 48) being connected to said air discharge line (44), and switchover means for interchanging the roles of the first and second inert gas adsorber columns (38, 48).

Description

DESCRIPTION OF THE INVENTION TO THE EURASIAN PATENT (45) Date of publication and issuance of the patent

2018.10.31 (21) Application Number

201791609 (22) Date of application

2016.01.08 (51) Int. Cl. G21F9 / (92 (2006.01)

G21C19 / 00 (2006.01) (54) VENTILATION SYSTEM AND RELATED OPERATION METHOD FOR APPLICATION DURING SERIOUS ACCIDENT IN NUCLEAR INSTALLATION (31) 10 2015 200 679.4 (32) 2015.01.16 (33) DE (43) 2017.11.30 (31) 10 PCT / ER2016 / 050255 (87) WO 2016/113189 2016.07.21 (71) (73) Applicant and patent holder:

FRAMATOM GmbH (DE) (72) Inventor:

Hill Axel (DE) (74) Representative:

Medvedev V.N. (Ru)

DE-A1-3418972

EP-A1-0307581

US-A-3 944646

WO-A1-2006097217

030998 B1

030998 Bl (57) The ventilation system (2) for a production facility serviced by production personnel in a nuclear installation, in particular for item (4) of the control at a nuclear power plant (6), should, in case of serious accidents with release of radioactivity, be possible for a period of time at least a few hours supply of decontaminated fresh air. In particular, the content of radioactive inert gases in the fresh air supplied to the production room should be as low as possible. To this end, according to the invention, the ventilation system (2) is equipped with an air supply line (10) from the external inlet (14) to the production room, which includes the first air blower (12) and the first column (for example, 38) of inert gas adsorption the production room to the external outlet (72) by an air exhaust line (44), which includes a second air blower (46) and a second column (for example, 48) inert gas adsorption, and switching means for changing the roles of the first and second columns (38, 48 a) inert adsorption gas.

At a nuclear power plant in case of failure situations or emergency situations, depending on the corresponding accident and the response measures initiated if necessary, one can expect that substantial release of radioactive decay products, in particular iodine, aerosols and inert gases, is possible. At the same time, due to leakages of the emergency containment shell of the reactor, it is necessary before proceeding to isolate and spread radioactivity in the buildings of the power station (for example, in buildings of auxiliary equipment, control stations, duty station, etc.). At the same time, along with the release of radioactivity associated with the aerosol, the release of inert gases, in particular, is a problem for the plant personnel.

Depending on the circumstances, significant release of inert gases also occurs at the beginning of the filtered pressure relief and during the formation of a cloud of inert gases over the territory of the power plant. Depending on the meteorological conditions, a continuous load cannot be completely excluded.

In order to initiate the so-called accident management measures, it is imperative that the conditions at the so-called control point or dispatcher duty post make it possible for production personnel to stay without unacceptable radiation exposure and radioactive contamination of personnel.

In case of beyond design basis accidents with a blackout of the power station (Station Black-Out (SBO)), target or ventilating and filtering units that are operated during normal operation are no longer available, in order to provide essential ventilation parameters to maintain availability of the duty station.

Previous concepts provide for the control of such scenarios isolation of the duty post. The supply is carried out, for example, with the help of mobile ventilation units, which are equipped with a variety of filters. Satisfactory retention of inert gases using these facilities is not possible.

Other concepts provide the duty station with accumulated compressed air. However, storage in pressure vessels for a longer period of time is very expensive and therefore limited. The modular and mobile structure of the system is practically not possible. In addition, the concept of pressure vessels require high labor costs for retrofitting in existing installations.

The objective of the invention is to provide the most simple and compact ventilation system for a control point of a nuclear installation or similar premises serviced by production personnel, which, in case of serious accidents with radioactivity release at least for a period of several hours, makes it possible to supply deactivated fresh air, so that there is the minimum possible radiation load present in the control room of the production staff. In particular, the content of radioactive inert gases in the fresh air supplied to the control point should be as low as possible. Further, the ventilation system should have the most passive nature and consume only a small amount of electrical energy. In addition, the most preferred way of operating such a ventilation system is provided.

In relation to the device, the problem is solved according to the invention with the help of the features of claim 1. In relation to the way the problem is solved using the characteristics of claim 10 of the claims.

Preferred embodiments are subject to the dependent claims and will be apparent from the subsequent detailed description.

According to the invention, the ventilation system has, inter alia, preferably an iodine and aerosol filtration module. The intake air on the air intake line is sucked in at the same time by an air blower and is conducted through a particle filter to separate the aerosols. After separation of the suspended particles, preferably radioactive iodine compounds are separated in the filtering pad of activated carbon. Impregnated activated carbon can be used to separate radioactive methyl iodides through isotope metabolism or salt formation. Behind the cushion of activated carbon it is preferable to hold the particle filter in series to hold the coal dust.

The air thus filtered is then supplied to the inert gas module in the second stage of the process. The inert gas module comprises essentially two adsorption columns in twin configuration, which are filled with adsorbent / adsorbents, preferably activated carbon. The adsorbent of the columns can also be formed from several layers of activated carbon and / or zeolite and / or molecular sieves.

The inlet air enters the first adsorption column, and inert gases, such as xenon, krypton, are slowed down by dynamic adsorption as it passes through the column. Behind the column it is advisable to have a filter to hold the particles of the adsorbent.

The air withdrawn from the supplied area of the room is carried out simultaneously through the second adsorption column and causes there a reverse flow of previously accumulated activity.

- 1 030998 inert gas, so that this column is again ready for loading after switching. Switching is done at the latest, shortly before the breakthrough of radioactivity in the first adsorption column, and then this column is flushed with a return stream of exhaust air. The switch is preferably invoked passively by means of a time element or by measuring activity.

Pre-flushing is preferably maintained by an air blower on the air exhaust line, with an increase in the volume of exhaust air flow due to low pressure enhances the process of reverse blowing of inert gases.

On the air exhaust line from the duty station, there is preferably a throttle, which leads to passive overheating of the exhaust air and, thus, to a decrease in the moisture in the exhaust air (dehumidification by expansion). As a result, there is a positive impact on the rate of desorption of inert gases in the lower connected, blown, adsorption column.

A throttle and / or air dryer is preferably located on the air supply line to the inert gas module in order to prevent too high humidity in the inert gas columns.

The inert gas module can optionally be equipped with a passive cold accumulator to increase the coefficient k. The coefficient k describes in this context the adsorption capacity of the adsorbent material for an inert gas in units of measure, for example cm ^{3 of} inert gas / g of adsorbent. The coefficient k depends on the temperature, pressure and humidity of the gas. As a rule, it is determined empirically.

The adsorption columns are operated preferably by a pressure change method, i.e. a low pressure of the blown column and an overload pressure of the loaded column (in each case relative to atmospheric pressure) in order to improve the coefficients k of the columns and reduce their dimensions. The overpressure in the adsorption column passed by the supplied air is regulated, for example, by a control valve on the air supply line.

Exhaust air is emitted with inert gases blown back into the environment surrounding the power plant at a sufficient distance from the intake air supply.

The ventilation system includes a suitable control unit and appropriate installation units for flow and pressure.

The advantages achieved with the aid of the invention are, in particular, that along with the air-borne activity in the form of aerosols and iodine / iodine compounds (in particular, organic iodine), radioactive inert gases are simultaneously retained from the air supplied to the duty station. Using the method of changing pressure and blowing twin columns, even long-lived isotopes of inert gases can be reliably separated from the flow of supplied air, such as krypton-85. The conditions necessary for removing inert gases from the sorbent / adsorbent are passively supported by overheating and expansion. The need for an electric operating current is essentially only for air blowers on the air inlet and outlet lines, as well as in an insignificant amount for a coordinated control unit and for switching means for switching between operating cycles. This need can be easily covered by an autonomous power supply module (for example, batteries and / or a diesel generator set) for at least 72 hours.

As a result, to maintain availability of the duty station, the following functions are provided: isolation of the duty station ventilation from the rest of the building, excess pressure compared to adjacent building premises (for example, <1 mbar), maintaining permissible monoxide and carbon dioxide concentrations, iodine retention, aerosol retention, containment of inert gases (for example, Kr, Xe), dose limiting (for example, <100 mSv / 7b), temperature limitation for complying with the I & C temperature qualifications, ensuring the above functions for at least of 72 hours.

As a generalization, additional benefits are: modular and mobile structure of the system, low labor costs and high flexibility when integrating into existing installations, low maintenance costs, costly storage of breathable air, possible coverage of large quantities of air (air exchange) and areas premises.

An example embodiment of the invention is explained further in more detail using the drawing. The drawing shows FIG. 1 - on the block diagram a schematic and greatly simplified general view of the ventilation system for the control point of a nuclear power plant; and FIG. 2 - modification (improvement) depicted in FIG. 1 system.

Depicted in FIG. 1 emergency ventilation system, briefly ventilation system 2, serves to

- 2 030998 supplying fresh air to the Main Control Room (MCR), also referred to as the control room or in English, point 4 of the control of the nuclear power plant 6 in situations of failure or accident, in particular, during the initial phase of a serious accident with release of nuclear decomposition products inside the building power plants, and in certain circumstances also in the environment.

In such scenarios, which, as a rule, are accompanied by the failure of the own power supply of the nuclear power plant 6 and, thus, also the failure of the ventilation system operated in the normal mode (not shown) for control point 4, it is especially important to be able to save point 4 controls for a certain period of time, up to about 72 hours after the start of the accident - without danger to the attendants, in order to initiate and control the initial response. It is possible that maintenance personnel should remain in point 4 of the control also until, after easing the initial maximum activity in the environment, safe evacuation is not possible.

To this end, on the one hand, ventilation system 2 for control point 4 is designed to supply fresh air deactivated and oxygenated, also called supply air, from the environment of control point 4 or the power plant building and is equipped with appropriate filtration and cleaning steps. On the other hand, the ventilation system 2 causes the discharge of air consumed and saturated with carbon dioxide, also called exhaust air, from point 4 of the control to the environment. In contrast to other previously used concepts, neither fresh air from the compressed air storage system, nor substantial recirculation and regeneration of air inside paragraph 4 of the control is provided.

Specifically, to the at least approximately hermetically encapsulated relative to the environment, the internal space of 8 point 4 of the control is also referred to as the fresh air supply line or shortly the fresh air line, the air supply line 10 along which during operation of the ventilation system 2 fresh air is sucked in blower 12 air from the environment and is fed into the inner space 8. The suction inlet or short inlet 14 of the line 10 for supplying air may be on some Dalen from paragraph 4 of the control, in particular outside the building power. However, depending on the development of the accident, fresh air aspirated through inlet 14 may be significantly loaded with radioactive decay products, in particular in the form of aerosols, iodine and iodine compounds, as well as inert gases. These components should be completely and as far as possible removed from the stream of fresh air, also called the supply air stream, before it is introduced into the internal space 8 of control point 4 through inlet 16 in the enclosing wall 18 (shown only partially).

To do this, downstream from the inlet 14, if you look in the direction of the flow of fresh air, the first filtration stage is connected in the form of an aerosol filter 20 on the air supply line 10, implemented here as an example by means of two connected in parallel with respect to the flow HEPA filters 22 suspended particles). Accordingly, HEPA filters 22 cause highly efficient separation of aerosol particles, also referred to as suspended particles, from the stream of fresh air, in particular with respect to the isotopes Te, Cs, Ba, Ru, Ce, La.

Further downstream, the second air filtration line is turned on in line 10 with an iodine filter 24 and a particle filter 26 connected below. Iodine filter 24 is implemented preferably in the form of an activated carbon filter cushion with a layer thickness, for example from 0.1 to 0.5 m. After the separation of suspended particles in the aerosol filter 20 in the iodine filter 24 occurs before, radioactive iodine compounds and elemental iodine, for example, are separated k> 8 with a contact duration of 0.1 to 0.5 s. For the separation of radioactive methyl iodides by isotopic exchange or salt formation, impregnated activated carbon can be used (for example, potassium iodide as an impregnating agent). A particle filter 26 connected behind the iodine filter 24 is provided to trap the coal dust from the activated carbon pad.

Downstream of the second filtration stage into the air supply line 10, an air supply blower or briefly air blower 12 is turned on to supply a stream of fresh air. The air blower 12, preferably driven by electricity, has a suction capacity in the range of, for example, from 100 to 6000 m ³ / h.

To provide the required operating current, an autonomous power supply independent of the normally operated operation and, preferably, also from the ordinary (system-wide) emergency power supply network, power supply unit 28, for example based on electric batteries / accumulators and / or diesel generator set, is provided. The power supply module 28 is activated in the event of a demand, preferably independently following an example of uninterrupted power supply, or alternatively driven by an agreed control unit 30.

Further downstream, air supply line 10 is optionally included, also referred to as the cold trap, of the air dryer 32, with which it is possible to separate the condensable components from the fresh air stream. It can be, for example, a passive cold trap with silica gel and / or ice as a drying agent. As a result, the moisture is reduced by

- 3 030998 stepping into the below connected functional blocks (see below) of the flow of fresh air. The same purpose is served by the throttle 34, existing alternatively or additionally and located in the example of implementation of the desiccant 32 of the air, if you look in the direction of the flow of fresh air, which affects the flow of fresh air on the principle of drying expansion. This may include, in particular, an adjustable throttle valve.

After filtering and drying, a stream of fresh air flows at an appropriate position of the respective installation organs (see below), for example, through a line section 36 in which an inert gas adsorption column or a short adsorption column 38 is included. Inert gases contained in the stream of fresh air due to physical and / or chemical adsorption, xenon and krypton, in the framework of a dynamically established equilibrium, are associated with the adsorbent present in the adsorption column 38 and thus slow down yayutsya portion 36 on the line until the adsorption capacity of the adsorption tower 38 has not yet been exhausted. In particular, one or more layers of activated carbon and / or zeolite and / or molecular sieves can be provided as an adsorbent.

For the adsorption column 38 is connected leading to paragraph 4 control line segment, which includes a filter of 40 particles to hold the separated particles of the adsorbent.

Finally, the fresh air flow deactivated in this way enters through the inlet 16 through the enclosing wall 18 of the control section 4 into its internal space 8, so that fresh, oxygenated breathing air is supplied to the internal space with a degree of radioactivity acceptable to the staff.

The air exchange is supplemented by exhausting breathing air, saturated with carbon dioxide, from point 4 of the control, connected to its interior space 8 and led out through an inlet 42 in the enclosing wall 18 to the environment of the exhaust air outlet 44, into which an air blower 46 is included to facilitate the exhaust. This is preferably a driven electrically powered air blower 46, which, like the air blower 12, is supplied with electric current from the power supply unit 28.

Since the adsorption capacity of the adsorption column 38 acting on the flow of fresh air is exhausted with a practical design value, as a rule, after a relatively short period of operation, the ventilation system 2 is designed to flush the adsorbed inert gases back into the environment without shutting down the system. For this purpose, there are two structurally practically identical adsorption columns 38 and 48, which are loaded with fresh air or exhaust air through the corresponding branches and connection lines, as well as installation organs, in this case as three-way valves. the adsorption columns 38 and 48 act, as already described, in the adsorption mode on the stream of fresh air, while the other column is simultaneously blown in the desorption mode or the blow-down mode from the air and is thus prepared for the next adsorption cycle. Due to the switching of the installation organs, the role of the adsorption columns 38 and 48 can be replaced and, thus, cyclically vary with respect to the corresponding column between the adsorption mode and the desorption mode.

In the exemplary embodiment shown in the figure, this functionality is realized due to the fact that one adsorption column 38 is located on the line section 36, and the other adsorption column 48 is in a counter-connected connection on the line section 50. Both sections 36 and 50 lines are combined on the one hand in a three-way valve 52, and on the other hand in a connection 54 located on the suction side of the air blower 46. In addition, on the one hand between the three-way valve 52 and the two mentioned adsorption columns 38, 48 are connected switchable both three-way valves 56 and 58 cross connection 60 between the two sections 36 and 50 lines, which through a T-shaped connection 62 is connected to the leading part of the air filter 10 to the particle filter 40. On the other hand, in a similar design between the adsorption columns 38, 48 and the connection 54, a cross connection 68 being switched by both three-way valves 64 and 66 is connected, which through the T-shaped connection 70 is connected to the air supply section 10 passing from the throttle 34.

With appropriately selected valve positions, incoming air coming from the throttle 34 flows, as already described above, through a T-shaped connection 70, a three-way valve 66, the bottom of the adsorption tower 38 in the figure, a three-way valve 58 and a T-shaped connection 62 to the filter 40 particles and from there further to item 4 controls. In another branch, the exhaust air coming from point 4 of the control flows through a three-way valve 52, a three-way valve 56, the upper adsorption tower 48 in the figure and a three-way valve 64 to the suction side of the air blower 46 and from there further to the waste pipe or to another outlet 72, which is expedient located at some distance from the entrance 14 for fresh air.

That is, the inert gases accumulated by adsorption in the previous cycle in the adsorption column 48 are desorbed in this mode of operation with largely exhausted air free from inert gases from the internal space of 8 points of control point 4 from the adsorbent and

- 4 030998 are evacuated by the return flow of exhaust air into the environment. The reverse purge is maintained by an air blower 46 located downstream of the adsorption column 48 blown by the reverse flow, and the increase in the volume of exhaust air flow due to the low pressure enhances the process of reverse purging of inert gases.

On the air discharge line 44 from the duty station it is located, as seen in the direction of the flow of exhaust air, upstream from the three-way valve 52 and, thus, upstream from the adsorption column 48 just in the purge mode, throttle 74, preferably in the form of adjustable the throttle valve, which leads to passive overheating of the exhaust air and, thereby, to a decrease in the moisture in the exhaust air (dehumidification expansion). As a consequence, increases the rate of desorption of inert gases in the lower connected adsorption column 48.

After switching the role of the adsorption columns 38 and 48 are reversed. Now fresh air, coming from the choke 34, flows through the three-way valve 64, the adsorption tower 48 and the three-way valve 56 to the particle filter 40 and from there to point 4 of the control. The air withdrawn from point 4 of the control, coming from throttle 74, flows through a three-way valve 52, a three-way valve 58, an adsorption tower 38 and a three-way valve 66 to the air blower 46 and from there to the outlet 72. The previously loaded adsorption column 38 is now blown backwards exhaust air, while the adsorption column 48 is available for the purification of fresh air and, thus, for re-loading.

To control the switching processes using three-way valves 52, 56, 58, 64, 66, a control unit 30 is provided, which expediently also controls both air blowers 12 and 46, and if necessary, further installation units for flow and pressure. The specialist should understand that the functionality of the switch can be equivalently implemented also with the help of other line topologies and installation bodies.

As indicated by the dashed fringing lines, the ventilation system 2 preferably has a modular structure of an inert gas module 76, an iodine and aerosol module 78, and a power supply module 28. The boundaries between the modules can be selected in detail naturally and also differently, and further modules or sub-modules may be present. Separate modules are placed with the possibility of transportation, for example in standard containers, so that simple transportation to the place of operation can be carried out and there is simple assembly by connecting the corresponding standardized line connectors.

In the embodiment shown in FIG. 2, a variant of the ventilation system 2 in addition to those known from FIG. 1 component has a retention unit for carbon dioxide (CO ₂ ), preferably with a predominantly based on chemical adsorption (chemisorption) or absorption by the column 82 adsorption of CO ₂ . Thus, it is possible to operate control point 4 for a certain period of time in the recirculation mode without feeding (filtered) breathing air outside, without the CO2 concentration in control point 4 exceeding the health-critical value of the production personnel. This has the advantage that under extreme loads of radioactivity outside the emergency containment shell of the reactor in the recirculation mode, radioactivity cannot penetrate into paragraph 4 of the control.

The integration of the CO ₂ adsorption column 82 into that known from FIG. 1, the system is preferably carried out in such a way that there is a recirculation line or an air recirculation line 80 leading to the air supply line 44 and leading to the air supply line 10, which includes the CO2 adsorption column 82.

The recirculated air blower 84, which is included in the air recirculation line 80, thus supplies, in recirculation mode, the selected CO2 from the control section 4, exhausted the exhausted air through the CO2 adsorption column 82 with a reduced CO2 content as the breathing air back to the control section 4. CO2 adsorption occurs almost at a pressure that prevails inside control point 4, that is, at about atmospheric pressure or slightly more pressure (preventing leakage / leakage, see below). As a consequence, the recirculating air blower 84 does not have to perform a substantial compression operation.

Specifically, in the example shown, the air recirculation line 80 is connected from the inlet side through a branch line (for example, a T-junction) to the section of the air exhaust line 44 between input 42 to control point 4 and throttle 74. On the output side, the air recirculation line 80 is connected via a branch line to an air supply section 10 located between the inlet 16 and the three-way valve 58, in this case in particular upstream of the particle filter 40. Additionally or alternatively, filters 86 may be included in the air recirculation line 80, in this case, for example, downstream of the CO2 adsorption column 82 (the direction of flow in the recirculation mode is indicated by an arrow next to the column).

Regarding the connection of the air recirculation system to the rest of the ventilation system 2, modifications are possible, of course, however, the depicted version has in particular the advantage that only two inputs 16, 42 through the enclosing wall 18 of paragraph 4 are required.

- 5 030998 control / through the protective shell. In addition, the advantage is that in the recirculation mode, the inert gas adsorption columns 38, 48 and the preceding components of the ventilation system 2 can be separated or isolated from the air recirculation system using appropriate shut-off valves or valves in accordance with the current and medium. .

Air recirculation line 80 itself is provided on the inlet and outlet side with shut-off valves 88, 90, in order to be able to isolate it, if necessary, from the rest of the piping system. Preferably, the check valves 88, 90 can be controlled with respect to flow (they are control valves), so that partial flows can also be set. This also applies to further valves, in particular to the stop valves 92, 94 described below.

You can provide your own, separate blower 84 recirculated air for line 80 recirculated air. However, it is most preferable to use the blower 46 on the air outlet line 44 used in the embodiment according to FIG. 1 solely as an exhaust air blower, in accordance with a dual purpose during the recirculation mode as a return air blower 84. To this end, the air recirculation line 80 is connected via suitable branches of the line or connection to the section of the air exhaust line 44 containing the air blower 46. This section of the line can be isolated by shut-off valves 92, 94 from the outlet 72 and the part of the ventilation system 2 that contains the inert gas adsorption column containing 48, 48 and forms a partial portion of the air recirculation line 80 during recirculation. The CO ₂ adsorption column 82 is positioned, as depicted, preferably downstream of the air blower 46 (or generally the recycle air blower 84) on its pressure side.

Preferably, referring to the shut-off valve 94, this is an adjustable three-way valve on the line branch, which, during desorption (reverse flow) of the inert gas adsorption column 38 or 48, releases the output 72 and blocks the connected branch of the air recirculation line 80. As a result, it is ensured that the radioactivity separated during desorption from the inert gas adsorption column 38 or 48 is blown into the environment and is not supplied via air recirculation line 80 to point 4 of the control. That is, the inert gas desorption mode (purging the inert gas adsorption column 38 or 48) and the CO ₂ adsorption mode (recirculation mode) are preferably not performed simultaneously.

However, the inert gas adsorption mode (loading of the inert gas adsorption column 38 or 48) and the CO ₂ adsorption mode (recirculation mode) can be performed simultaneously without problems. In this case, in paragraph 4 of the control, fresh air is injected, filtered by at least one of the two columns 38 or 48 of the inert gas adsorption and the air supply line 10. The air withdrawn from item 4 of the control is supplied with the shut-off valve 88 open by means of an air blower 46 via an air recirculation line 80. However, depending on the position of the check valve 94, made in the form of a three-way control valve, a more or less large partial flow (which, if necessary, may also have a value equal to zero) is discharged through outlet 72 to the surrounding atmosphere, and the remaining partial flow is conducted through the column 82 CO ₂ adsorption back to control point 4. The shut-off valve 92 is closed at the same time, so that, as mentioned above, an undesirable return of radioactivity from the inert gas adsorption columns 38 or 48 to the control point 4 is prevented.

A further possible mode of operation involves the simultaneous adsorption and desorption of columns 38 or 48 of inert gas adsorption with repeated alternation, as already described in connection with FIG. 1. In this mode of operation, as already mentioned above, CO2 adsorption in recirculation mode preferably does not occur.

However, it was found that physical adsorption in columns 38 or 48 of adsorption of inert gas at elevated pressure (for example, 8 bar) is much more efficient than at atmospheric pressure, while desorption preferably takes place at relatively low pressure, in particular with a slightly reduced pressure relative to atmospheric pressure. As a consequence, after each alternation (switching), a certain period of time must be planned, for example, from 10 to 30 minutes, for the required pressure increase, acting as a compressor by the air blower 12. In this pressure boosting phase, at which the holding capacity of the inert gas adsorption columns 38 or 48 has not yet reached its maximum, the ventilation of control point 4 is preferably carried out only by adsorption of CO ₂ in recirculation mode. At the same time, although the oxygen content of air in the control station 4 occupied by production personnel slowly decreases due to its consumption, however, the CO2 content is reliably kept below the critical value. Later, after the working pressure required for effective holding of inert gases is reached, a supply of filtered air through the columns 38 or 48 of inert gas adsorption is preferably connected (simultaneous adsorption of inert gases and adsorption of CO2, as described above). As a result, the previously reduced oxygen content of the air in paragraph 4 of the control is restored again. Later, the regeneration phases (desorption) can be carried out with the air recirculation disabled, and the adsorption columns 38 and 48 can change.

- 6 030998

In other words, the preferred mode of operation of the ventilation system 2 according to FIG. 2 includes the fact that during the required period of time for increasing the pressure in the adsorption columns 38, 48, point 4 of the control is supplied, preferably exclusively, in the recirculation mode. After increasing the pressure, fresh air preferably during / along with chemical adsorption of CO ₂ is supplied over the inert gas containment section by the adsorption columns 38, 48. The increased volumetric flow is preferably used to maintain the oxygen concentration and to increase the pressure in control point 4. As a result, a directional flow is created with increased pressure in control point 4 as compared with the external environment, which reliably prevents penetration of radioactivity from the outside into control point 4 (inleakage (leakage)). Simple systems that only work with CO ₂ filtration can provide this feature not reliably enough.

The adsorbent used to adsorb CO ₂ in the adsorption column 82 can be, for example, sodium lime (in English soda lime), a zeolite / molecular sieve or a regenerable adsorbent. As further examples of possible adsorbents, primarily oxides, peroxides and superoxides (for example, potassium superoxide) can be used. Regenerated adsorbents can consist of metal oxides or mixtures thereof. For example, silver oxide reacts with CO ₂ to form silver carbonate. In principle, mixtures of these adsorbents can also be used, or multi-stage adsorption columns with the same or different adsorbents can be realized in different stages.

With the appropriate suitability of the adsorbent, chemisorption occurring in the adsorption column 82 can be reversibly performed at elevated temperatures, and the adsorbent can be practically regenerated. For this purpose, simple modifications of laying air recirculation lines are advisable, so that such regeneration phases outside the recirculation mode described above can be performed without load for item 4 of the control.

In summary, the systems of FIG. 1 and 2 ensure that, in addition to the airborne radioactivity of aerosols and organoids, inert gases are also kept out of the air for breathing of the on-duty post. Moreover, with the modified system according to FIG. 2 CO ₂ is removed from the breathing air by chemical adsorption / absorption.

Due to the inclusion of direct CO ₂ adsorption, control point 4 may be operated in recirculation mode in extreme emergencies, until the oxygen concentration of the station on duty goes down to the lower limit value (approximately 17-19 volume percent), so that fresh air will be needed outside. The inert gas containment module with adsorption columns 38, 48 is operated in this case primarily for coating and increasing the oxygen content. As a consequence, the required module power can be significantly reduced in terms of the energy of the drive and the amount of activated carbon. The required compression energy to create adsorption at a variable pressure can be minimized. As a result, the units required for autonomous power generation can be performed with smaller sizes.

Despite the fact that the description has so far been directed to the ventilation of the (central) control station of a nuclear power plant, it is nevertheless clear that ventilation system 2 can also be used for emergency ventilation of other rooms inside a nuclear power plant or in a whole nuclear installation, for example, also inside storage depots of fuel elements, spent nuclear fuel regeneration facilities, nuclear fuel treatment facilities, etc., for example, for emergency ventilation of buildings with auxiliary equipment rooms, with switchgear, control and measurement points or other premises of management and control. Summarizing the key word for such premises is also used the designation of the production room.

List of reference positions ventilation system control point nuclear power plant internal space air supply line air blower inlet input fencing wall aerosol filter

HEPA filter iodine filter particle filter power supply module

- 7 030998 control unit air dryer choke line section adsorption column particle filter input air exhaust line air blower adsorption column line section three-way valve connection three-way valve three-way valve cross connection

T-shaped connection three-way valve three-way valve cross connection

T-shaped connection exit choke module of inert gas iodine and aerosol module air recirculation line adsorption column CO ₂ blower of recirculation air filter shut-off valve shut-off valve shut-off valve shut-off valve

Claims (14)

CLAIM 1. Ventilation system (2) for a production facility in a nuclear installation serviced by production personnel, including for item (4) of the control at a nuclear power plant (6), containing at least the following components: An air supply line (10) drawn from the external inlet (14) to the production area, which includes the first air blower (12) and the first inert gas adsorption column, conducted from the production room to the external outlet (72), air discharge line (44), which includes a second air blower (46) and a second inert gas adsorption column, and switching means for changing the roles of the first and second columns (38, 48) of inert gas adsorption, characterized by the fact that Line (80) of the air recirculation, which includes a column (82) and a CO2 adsorption blower (84) circulating air, the second blower (46) is switchable into the air line (80) as recirculation air blower (84) circulating air. 2. The ventilation system (2) according to claim 1, wherein the air recirculation line (80) is connected on the inlet side to the air outlet line (44) and on the outlet side to the air supply line (10). 3. A ventilation system (2) according to claim 1 or 2, the first air blower (12) being located, if viewed in the direction of flow of the supplied air, upstream from the first inert gas adsorption column. 4. The ventilation system (2) according to claim 3, wherein between the first air blower (12) and the first inert gas adsorption column, the throttle (34) and / or the air dryer (32) are included in the air supply line (10). 5. A ventilation system (2) according to any one of claims 1 to 4, wherein the second air blower (46) is located, when viewed in the direction of the flow of exhaust air, downstream of the second inert gas adsorption column. 6. The ventilation system (2) according to any one of claims 1 to 5, moreover, when viewed in the direction of the flow of exhaust air, upstream from the second inert gas adsorption column, the choke (74) is turned on in the air discharge line (44). - 8 030998 7. A ventilation system (2) according to any one of claims 1 to 6, wherein the iodine filter (24) and the aerosol filter (20) are included in the air supply line (10). 8. The ventilation system (2) according to claim 7, wherein the iodine filter (24) and the aerosol filter (20) are located, when viewed in the direction of the flow of supplied air, upstream from the first air blower (12). 9. A ventilation system (2) according to any one of claims 1 to 8, comprising an autonomous power supply module (28). 10. A ventilation system (2) according to any one of claims 1 to 9, wherein the switching means include several three-way valves (52, 56, 58, 64, 66). 11. The method of operation of the ventilation system (2) for the production facility serviced by production personnel in a nuclear installation, including the control point (4) at the nuclear power plant (6), and the ventilation system (2) contains at least the following components : An air supply line (10) drawn from the external inlet (14) to the production area, which includes the first air blower (12) and the first inert gas adsorption column, conducted from the production room to the external outlet (72), air discharge line (44), which includes a second air blower (46) and a second inert gas adsorption column, and switching means for changing the roles of the first and second columns (38, 48) of inert gas adsorption, and simultaneously through one of the two mentioned inert gas adsorption columns the supplied air is lowered and, thus, this column is loaded with radioactive inert gases, and the exhaust air is passed through another inert gas adsorption column and, therefore, the column is blown back in return, and the role of the two mentioned columns of (38, 48) adsorption of inert the gas is changed by switching as soon as the adsorption capacity of the actually loaded inert gas adsorption column is exhausted, characterized in that the air recirculation line (80) passes and returns from the production room ear, which includes a column (82), the adsorption of CO ₂ and a blower (84) circulating air, and by a first blower (12) of the air in at least one of said two columns (38, 48) an inert gas absorption is performed pressure increase, and at the same time in the mode of recirculation of air carry out the reduction of CO2 content through a column (82) of CO2 adsorption. 12. The method according to claim 11, wherein the ventilation of the production room during the pressure increase is carried out exclusively with CO2-recirculated air. 13. The method according to claim 11 or 12, and at the same time supplied air is supplied to the production room through at least one of the two mentioned columns (38, 48) of inert gas adsorption and, in the air recirculation mode, the CO2 content is reduced by means of the adsorption column (82) CO2. 14. A method according to any one of claims 11-13, wherein the first air blower (12) is used as a recirculating air blower (84). FIG. one - 9 030998 FIG. 2